Water And Wastewater Engineering Set 2 MCQs

Q1 | If the depth of flow in a circular sewer is 1/4th of its diameter D, the wetted perimeter is

??????

????

Q2 | At the junction of sewers

Top of smaller sewer is kept lower

Top of larger sewer is kept lower

Tops of both the sewers are at the same level

None of these

Q3 | The sewage treatment units in which anaerobic decomposition of organic matter is used, arecalled

Imhoff tanks

Trickling filters

Sludge sedimentation tanks

None of these

Q4 | The sewer which received discharge from two or more main sewers, is known as

A trunk sewer

An outfall sewer

A main sewer

An intercepting sewer

Q5 | The grit and silt of the grit chambers, may not be used for

Raising low lying areas by dumping

Concreting

Both (a) and (b)

Neither (a) nor (b)

Q6 | For treating the sewage of a large city, you will recommend

A sedimentation tank and an activated sludge treatment plant

A plant consisting of Imhoff tanks with low rate trickling filters

Sedimentation tanks with high rate trickling filters

None of these

Q7 | Imhoff cone is used to measure

Total organic solids

Total solids

Total in organic solids

Settleable solids

Q8 | 1000 kg of sewage contains

0.112 kg in suspension

0.112 kg in solution

0.225 kg in solution

Both (a) and (c) of above

Q9 | For the COD test of sewage, organic matter is oxidised by K2 Cr2O7 in the presence of

H2SO4

HNO3

HCl

None of these

Q10 | The sludge does not contain waste water from

Bath rooms

Wash basins

Kitchen sinks

Toilets

Q11 | In sewers the velocity of flow should not be

More than the self-cleansing velocity

Less than the self-cleansing velocity

Less than 10 m/sec

More than 20 m/sec

Q12 | In sewers the effect of scouring is more on

Top side

Bottom side

Horizontal side

All sides

Q13 | The sewer which resists sulphide corrosion, is

Brick sewer

Cast iron sewer

R.C.C. sewer

Lead sewer

Q14 | In a sedimentation tank (length L, width B, depth D) the settling velocity of a particle for adischarge Q, is

Q/(B × D)

Q/(L × D)

Q/L

Q/(B × L)

Q15 | The formula which accepts the value of rugosity coefficient n = 0.012 to be used in Manning'sformula, is given by

Bazin

Crimp and Bruges

William-Hazen

Kutter

Q16 | The amount of oxygen consumed by the aerobic bacterias which cause the aerobic biological decomposition of sewage, is known

Bio-Chemical Oxygen Demand (B.O.D.)

Dissolved Oxygen (D.O.)

Chemical Oxygen Demand (C.O.D.)

None of these

Q17 | Water content of sewage is about

90%

95%

99%

9.90%

Q18 | Skimming tanks are

Used to remove the grease and oil

Those from which sludge is skimmed out

Tanks provided with self-cleansing screens

Improved version of grit chambers

Q19 | The most efficient cross-section of sewers in a combined sewerage system is

) Parabolic

Circular

Rectangular

New egged

Q20 | The detention period for plain sedimentation water tanks, is usually

4 to 8 hours

8 to 16 hours

16 to 24 hours

24 to 36 hours

Q21 | The factor responsible for purification of sewage in river is

Hydrology

Dissolved oxygen in water

Temperature

All the above

Q22 | Hume steel pipes are

Steel pipes

Steel shell coated from inside with cement mortar

Steel shell coated from outside with cement mortar

Both (B) and (C)

Q23 | To maintain aerobic biological activity, the moisture content of the compost mass should beabout

45%

50%

55%

60%

Q24 | Pick up the correct statement from the following:

The larger the sewer in size, more will be

The smaller the sewer in size, less will be velocity

The larger the sewer in size, no deposition will take place

The larger the sewer in size, deposition will take place

Q25 | The pH value of sewage is determined with the help of

Imhoff Cone

Turbid meter

Potentiometer

None of these